A new model of fluid flow to determine pressure balance characteristics
TypeArticles dans des revues avec comité de lecture
Some projects such as the EUROMET project 463 have underlined the lack of agreement between experimental measurements and calculations by the finite element method (FEM), used to determine the piston fall rate of a high-pressure balance used in primary standards. This is significant because the piston fall rate is an essential parameter to characterize experimentally the mean gap between the piston and the cylinder and to determine the effective area (A p) at each pressure (p) point. By improving the method used to estimate the piston fall rate it is possible to improve the determination of the gap, the effective area and consequently the pressure distortion coefficient. One possible cause of the lack of agreement between the calculated and measured piston fall rates could be inappropriate modelling of the fluid flow. In fact, the former quasi-1D Stokes model assimilates the gap between the piston and the cylinder as formed by two parallel walls, which is an approximation. In addition, the velocity of the piston wall was neglected. In order to evaluate the influence of this model, the equations of the fluid flow are modified and are presented in this paper. Equations that were defined in a parallel-plane model are defined in an annular gap model. In addition to this, corrections due to the velocity of the piston wall are inserted. This research work is applied on a Desgranges et Huot DH 7594 piston-cylinder unit of PTB with a pressure up to 1 GPa, in the continuity of the EUROMET project 463 in order to quantify the influence of each correction that has been inserted in the new equations. This is carried out using the FEM. This analysis will allow us to evaluate the improvement of our knowledge of the behaviour of piston gauges and consequently to better evaluate the uncertainties due to the models.
Fichier(s) constituant cette publication
Cette publication figure dans le(s) laboratoire(s) suivant(s)
Visualiser des documents liés par titre, auteur, créateur et sujet.
Numerical investigation of the real and ideal gap profiles in the calculation of the pressure distortion coefficient and piston fall rate of an LNE 200 MPa pressure balance WONGTHEP, Padipat; RABAULT, Thierry; NOGUERA, Ricardo; SARRAF, Christophe (IOP Publishing, 2013)This paper aims to investigate, by means of numerical simulation, the effect of gap profiles on the calculation of the pressure distortion coefficient (λ) and the piston fall rate (vf) of two piston-cylinder units used in ...
CHABI, Fatiha; CHAMPMARTIN, Stéphane; SARRAF, Christophe; NOGUERA, Ricardo (Elsevier, 2015)We evaluate here three hemodynamic models used for the numerical simulation of bare and stented artery flows. We focus on two flow features responsible for intra-stent restenosis: the wall shear stress and the re-circulation ...
CHABI, Fatiha; CHAMPMARTIN, Stéphane; SARRAF, Christophe; NOGUERA, Ricardo; MAUREL, Blandine (2014)This work assesses three hemodynamic models for the numerical modeling of intra-stent flows. These are the classical Poiseuille model (PM), the simplified pulsatile model (SPM) and the complete pulsatile model (CPM) based ...
Experimental study of blade rigidity effects on the global and the local performances of a thick blades axial-flow fan NOURI, Hussain; RAVELET, Florent; SARRAF, Christophe; BAKIR, Farid (ASME, 2010)An experimental investigation on the aerodynamic performances of thick blades axial-flow fans was carried out in this study. Two fans are considered, the first one is rotomoulded (in plastic) and the second one is milled ...
Experimental study of blade thickness effects on the overall and local performances of a Controlled Vortex Designed axial-ﬂow fan SARRAF, Christophe; NOURI, Hussain; RAVELET, Florent; BAKIR, Farid (Elsevier, 2011)The purpose of this work is to study the effects of blade thickness on the performances of an axial-ﬂow fan. Two fans that differ only in the thickness of their blades were studied. The ﬁrst fan was designed to be part of ...